In the case of such a rotor of the type mentioned at the outset and already known from German utility model No. 84 27 703, the individual permanent magnets are fixed by means of a positioning cage on the cylindrical rotor body which serves as the carrying member. This positioning cage is constructed in one piece and consists of end rings and longitudinal webs which connect these to form one body. Preferably, it is injection moulded onto the rotor body after the magnet segments have been previously fitted. Alternatively, it can also be pushed on with the permanent magnets inserted into the rotor cage and then fixed on the outer periphery of the rotor body. A disadvantage of this is that the manufacturing costs are substantial and that the moment of inertia of the rotor as a whole is increased by the weight of the cage, which is particularly significant since the positioning cage is disposed in the outer periphery of the rotor.